Compound 1 shows an adenosine A2 receptor antagonistic activity and is useful for the treatment of various diseases induced by hyperactivity of adenosine A2 receptor such as Parkinson disease, senile dementia, depression, asthma and osteoporosis (European Patent No. 0,590,919; Japanese Published Unexamined Patent Application No. 040,652/97). It is known that xanthine derivatives including Compound 1 are used as a powder by pulverization for inhalation administration (European Patent No. 0,590,919). Crystals of Compound 1 have been known as well (Japanese Published Unexamined Patent Application No. 040,652/97). Crystals of Compound 1 synthesized by the process disclosed in the above citations have characteristics that (1) the solubility thereof in water is low and that (2) the form thereof is needle-like where a short diameter is several μm and a long diameter is not less than several hundred μm, and therefore, there are problems that, during the operation of steps for preparing pharmaceutical formulations, crystals of Compound 1 are aggregated. It has been said that drugs having low solubility in water generally have low bioavailability because of low solubility and slow dissolving velocity in digestive tracts. Also with regard to Compound 1, enhancement in its solubility, dissolving velocity or the like, for improvement of bioavailability and the like are demanded. On the other hand, aggregation of crystals of Compound 1, which takes place during the operations of the steps for preparing pharmaceutical formulations, affects on fluidity of crystals of Compound 1 and additives. Therefore, there are problems in view of handling of crystals of Compound 1 in the steps for preparing pharmaceutical formulations and in view of dispersibility of Compound 1 in the solid formulations. It is also known that Compound 1 is unstable particularly under light and a double bond moiety (vinylene moiety) in its structure is apt to be isomerized [Bioorg. Med. Chem. Lett., volume 7, pages 2349-2352 (1997)], and careful attention is needed for handling in preparing the pharmaceutical formulations comprising Compound 1.